Propeller hub



NOV 21, 1950 P. F. HACKETHAL ETAL l2,530,529`

PROPELLER HUB Filed sept. 17. 194e 3 Sheets-Sheet l l @N N Y u .A W.. H MMT i /A//Mmwml JHM y ffii/ffl l?? MMM@ @@9- Nov. 2l, 1950 P. F. HACKETHAL Erm.

PROPELLER HUB 5 Sheets-Sheet 2 Filed Sept. 17, 1946 IE- MU Nov. 2l, 1950 v P. F. HAcKl-:THAL Erm. 2,530,520

PROPELLER HUB Filed Sept. 17, 1946 3 Sheets-Sheet 5 A a/allions ,Q4/JL #Acker/mf. ,Parra/14D HIRE/V Patented Nov. 21, 1950 PROPELLER HUB Paul F. Hackethal, Cockeysville, and Romuald Karey, Baltimore, Md., assignors to Everel Propeller Corporation, Baltimore, Md., a corporation of Maryland Application September 17, 1946, Serial No. 697,488

3 Claims.

' This invention relates in general to propellers for aircraft and more particularly has reference to the construction of a hub for the mounting of blades of a variable pitch propeller.

Automatic pitch changing propellers have been developed in which the shanks of the blades are secured in flanged sleeves which are mounted for rotation within suitable sockets formed in the hub of the propeller. The construction of the blade shank-receiving-sleeves is such that the longitudinal axes of the blades are at an angle to the rotational axes of the sleeves with the result that the rotational position of the blades with respect to the hub determines the pitch of the blade and as a consequence the pitch angle of the blades is affected by various conditions encountered in flight. These conditions are principally the relationship of the aerodynamic forces acting cn the blade, the centrifugal force acting on the blades, and the centrifugal force due to the counterweights secured to the blades.

While a high degree of perfection has been obtained in such propellers, both in construction and operation, certain diinculties have been encountered in the assembly and adjustment of the blades with respect to the hub and to each other and in balancing the propeller while still maintaining the individual weight and balance of the blades Within such prescribed Weight tolerances that a blade of a propeller may be replaced in service Without the necessity of completely rebalancing the assembly.

Also in the prior constructions diiculty has been encountered in the sealing of the bladeshank-reeciving-sleeves within the hub sockets with little frictional resistance to free rotation about their axes and with effective sealing. InA addition, difficulty has been encountered in producing an effective seal, practical for its intended purpose, at low cost.

It is desirable to provide a connection between the blades of a propeller to insure movement in unison of the blades about the turning axes of their mounting sleeves to eiect variations in pitch. Numerous devices for this purpose have been developed but for various reasons, such as excessive Weight, disturbance of balance of the propeller assembly and excessive resistance to pitch varying movements of the blades, such prior devices have not been entirely satisfactory. Furthermore, the means for limiting pitch vvarying movements of the blades have been of various forms, but here again, diiiiculties due to disturbance ofbalance and excessive Weight have been encountered.

The principal object of the present invention is to provide a propeller hub construction which is free from the above pointed out disadvantages inherent in the prior art.

Another object of the present invention is to provide a propeller hub construction for the mounting of the blades of an automatic variable pitch propeller in which the propeller blades have their Shanks received in sleeves which in turn are mounted within sockets in the hub and are sealed Within the hub so as to permit free rotation of the sleeves within the hub and yet effectively seal the joint between the sleeves and the hub to prevent leakage of oil therethrough.

A further object of the present invention is to provide an improved mechanism for loading the bearings which serve to rotatably mount the blade-shank-receiving-sleeves within the hub of the propeller.

Still another object of this invention is to provide an improved bearing loading construction equipped with means for positively retaining the same in adjusted positions.

A still further object ofthis invention is to provide an improved mechanism interconnecting the sleeves of the blades of the propeller for effecting uniform, synchronous movement of the blades about their rotary axes during pitch changing movements.

It is also an object of the present invention to provide an improved device for limiting the movements of the blade-shank-carrying-sleeves during pitch changing movements. l

The present invention also has as an object the combination and correlation of the features set forth in the preceding objects to provide a highly improved construction of the hub of an automatic variable pitch propeller.

With these and other objects in view, the pres-` ent invention comprises the parts and combinations herein described and illustrated in the drawings.

In the drawings:

Figure 1 is a transverse sectional view taken through the bladeshank-receiving-sleeves and the portion of a propeller hub mounting, said sleeves constructed in accordance with the present invention, said View being taken on line I-I of Figure 2 of the drawings.

Figure 2 is a view taken transversely to the axis about which the propeller blades rotate during pitch changing movements.

Figure 3 is a side elevational view of a propeller hub constructed in accordance with the present invention, parts being broken away to illustrate detail of construction.

Figure 4 is a fragmentary sectional view illustrating in greater detail the construction and arrangement of the seals for preventing leakage of oil from the bearings within the hub.

Figure 5 is an enlarged detailed cross sectional view of a packing ring employed in the present invention.

As shown in the drawings, a. propeller hub constructed in accordance with the present invention has been designated generally by reference character i. The hub comprises a barrel 2 and a mounting flange 3 which serves to connect the barrel to a corresponding ilange carried by a drive shaft of an engine. Flange 3 may be formed as an integral part of the barrel 2 orV it may be secured thereto in any suitable manner such as by welding, brazing and the like. Barrel 2 has an integral bore i extending diametrig cally` or transversely of the axisof rotation of the hub l. This bore d is of substantially the same internal diameter throughout its length withA the exception of a seat 5 provided intermediate its end portions and an inwardly extending ilange t adjacent the seat.

The ends of bore i withinthe barrel 2 serve as sockets to receive sleeves l in which the propeller bl ade Shanks are mounted. Adjacent end of the bore l annular grooves 8 are provided for the recepion of split resilient rings S which serve as blocking means to retain the sleeves within the bore fi.

Sleeves 'i are provided with internal threads itl which are adapted to cooperate with the threaded whichsuitable bolts 5S extend and` serve to clamp 1.1;.-

the rings. it and theradial extensions i5 in desired positions with respect to the cuffs il and the propeller blades carried therein. The extreme outer portions of the-'radial extensions i5 are provided with bores it for the reception of bolts byv means of which counterweights (not shown) are secured to .sa-id extensions.

As clearv shown in `i-of the drawings,V the inner ends of the sleeve l are provided with ozztwardly extending circumferential flanges Immediately adjacent the flange il, the exterior of each sle :ve 'i' is provided with a seat i5 for the reception of one race E9 of a ball thrust bearing assembly I9'. The other race 2d of said ball thr-ust bcaring assembly has an external diameter approximating the internal diameter of the barrel 2. Lying in Contact with the race 25 is a retaining ring 2i which cooperates with the snap ringrS to retain the ball bearing assembly iii and the sleeves 'E within the .outer Vend of the barrel 2. This retaining assembly serves to effectively block any tendency for the sleeve l to move outwardly of the end of the barrel 2.

As more clearly shown in Fig. i of the drawings,

the outer peripheral portion of one end face of f the race 2? is provided with an annular recess 22 of a trapezoi'dal cross section for the reception of a similarly shaped paci-zing ring 23. This packing ring cooperates. with the inner surface of the barrel 2, wilh the surfaces of the groove 22 and with the adjacent end face of the retaining ring 2| to provide an effective seal between these three elements.

The inner peripheral portion of the retaining ring 2i is provided with an annular groove 24 of rectangular cross section in the end face thereof, abu'ting the race 2E. Positioned within the annular groove 24 is a packing ringv 25 of a special construction as more clearly illustrated in Fig. 5 or the drawings. This packing ring has an inner peripheral portion 2E of cylindrical formation and endk faces 21 and 28 which flare outwardly. Actually, the end face 2l may be pla-in but, in any event, the end face 28 is flared outwardly. It is preferable that the end face 23 be of greater eX- tent than the face 2l to provide the coniiguration shown in Figs. 4 and 5 of the drawings. The outer peripheral surface 29 of the ring 25 is in the form of a circumferential groove or trench which cooperates with the resilient tensioning member which, as shown in the drawings, comprises -a coil spring Bil.

As illustrated in Fig, 4 of the drawings, the packing ring 25 is positioned within the annular groove 2d with the inner cylindrical` face surrounding the sleeve 'i' and with the outer peripheral portion extending into the groove 2Q. The coil spring 53d is then placed within the groove or trench E9 and placed under tension to compress the ring about the sleeve l. The compression of the packing ring 25 serves to cause the outer-pe.- ripheral portions of the end faces 2l and 28 to be pressed axially against the surfaces of the race 2) and the retaining ring El to provide an effective sea-l between these members and the sleeve l.

By virtue of the provision of the sealing or packing rings 23 and 25 and the arrangement of the same within the grooves provided therefor, a seal is aiorded which, while very effective for preventing the leakage of oil past the saine, even under pressure createdV by centrifugal action on the oil during rotation of the propeller, nevertheless, does not provide excessive friction for retarding or resisting the free rotation of the sleeve l' within the barrel 2..

In order to load the anti-friction bearings So as to eliminate any looseness in the assembly and te maintain the bearings loaded even when the propeller is stationary, the present invention contemplates the provision of an adjustable expansible assembly extending between the inner ends of the blade carrying sleeves l. As best illustrated in Fig. 1 of the drawings, the inner or" the sleeves 'i are bored to provide recesses Si in which are received the outer race 32 of an anti-friction ball bearing assembly 32a. The inner race 33 of the ball bearing assembly of one of the sleeves 'i is tted on to the outer of two telescopically mounted elements of an adjustable expansible device. Said outer element 34 is provided with a shoulder 35 to abut the inner end of the race 33 Whereas the recess 3l is provided with a shoulder for engaging the outer endof the race 32. Element 34 is internally threaded for: engagement with the externally threaded port'on of the inner element 36. In addition to the threaded engagement between the outer and inner elements 34 and 36, said elements are provided with cooperating telescoping cylindrical surfaces.

Inner element 3S is provided with a, seat 3'! for the reception of the inner race 33 of a second ball bearing. assembly 32a which is mounted within the recess 3| of the other blade receiving sleeve 1.

The threaded end of the outer telescopcally mounted member is provided with a plurality of slots or serrations S8 which are best shown in Fig. 2 of the drawings. These slots or serrations Serve as a means by which a tool or other device may be engaged with the element 34 to eiTect rotation thereof. The inner element 36 is provided with an inner bore of reduced ldiameter which is provided with a plurality of splines 3Q by means of which said element 35- may be engaged with a wrench or other tool for effecting rotation thereof. By engaging the elements 34 and 35 with proper tools cooperating with the serrations 38 and the splines 39, said telescopically mounted threadedly interconnected elements may be rotated with respect to each other to vary the distance between their outer ends. By virtue of the interpositioning of the ball bearing assemblies 32a, and 32h between the ends of the elements 34and 35 and the ends of the sleeves 7, outward axial movement of the ends of the telescopically mounted elements will tend to force the sleeves l toward the outer ends of the barrel 2 and thereby load the anti-friction bearings l5 positioned between the sleeves and said barrel.

After adjustment of said elements 34 and 3S with respect to each other, they may be positively secured by the insertion of a bolt-like locking element 4S having a splined outer surface cooperating with the splines 39 and (a head 4! engaging with the slots or serrations 35 of the element 34. The head 4| is retained within the slots 38 by placing a nut 42 on the threaded end of the bolt-like element 40. Suitable look washers or other securing means may be provided for retaining the nut in place on the boltlike locking member 4G.

After the telescopically mountedv elements 34 and 35 have been adiusted with respect to each other to properly load the bearings I9', the openings through sleeves 'i aiording access to the elements 34 and 35 may be closed by suitable closure members i3 which are in the form of discs having peripheral portions adapted to be received within counterbores formed in the inner ends of the sleeves. interposed between the bottoms of said counterbores and the discs 43 are suitable sealing elements 44 against which the edges of the discs are pressed and retained by split snap retainer rings 55. Small knobs 45 may be associated with each of the discs 43 to facilitate the placing and the removal of the same from closing position. By providing the discs 43 sealed within the inner openings of the sleeves l, oil or other lubricant within the barrel 2 may be f tained therein and prevented irom creeping out between the sleeve l and the shanks of the propeller blades mounted therein.

On the inner end of each of the sleeves i,

there is eccentrically mounted a pin ll whichv may be screw-threaded or otherwise anchored in place. Pins are located with respect to each other as illustrated in 2 of the drawings. A pair of links are each connected at one end to one of the pins @l and are connected at their other end both to a wrist pin 49 which extends through a plunger or piston 5?. The plunger or piston eil is mounted within the bore of a small cylinder 5I which extends radially with respect to the barrel 2. Although the cylinder 5l is shown located diametrically with respect to the mounting flange 3, said cylinder 5l may be located at any position about the periphery of the barrel 2. As a matter of fact, it may even be mounted within the connection between the barrel 2 and the ange t. The only requirement is that the cylinder 5I extend radially with respect to the barrel 2.

Piston or plunger 50 may be formed of two semi-cylindrical portions which are spaced apart to provide a free ow path for any uid such as air or oil that may be within the barrel 2 of the hub so that there will be no damping action on the movement of said plunger. Instead of forming the piston 5i! of two semi-cylindrical portions it may be of annular construction having one or more passages extending axially therethrough. It will be appreciated that the assembly comprising the pins 4'! on the inner ends of the sleeves l, the links 48, the wrist pin 49 and the piston 50 serve to synchronize movement between the two sleeves l. The pins, links, plunger and cylinder 5l should be of such size and adequately constructed to take care of the loads that may be imposed thereon due to any tendency for one of the sleeves to be moved out of synchronism with the other by a virtue of forces encountered by the propeller blades which are mounted within the sleeves 1.

The outer portion of the cylinder 5I is provided with a suitable closure member 52 which is secured to the ilanged outer end 53 of the cylinder by means of screws 54 which are retained in assembled relationship by means of cotter pins or wire 55. The closure 52 apart from sealing the hub assembly against the leakage of lubricant therefrom also serves as a stop against which the upper surface of the piston 50 abuts to limit the rotary movement of the sleeves 1.

For limiting inward movement of the plunger 55 and rotary movement of the sleeves 1, a semicylindrical disc 55 is mounted within the barrel 2. Disc 55 has an outer flanged portion which is received on seat 5 against the shoulder or flange 6. This flanged portion of disc 56 extends about the entire periphery thereof including a transverse, nat portion 51 which serves as an abutment or stop against which the ends of the links 48 surrounding the pins 41 may abut.

In addition to serving as an abutment forengagement with the inner ends of the links 48, disc 55 is provided with a central opening surrounded by a fairly wide flange 58 which serves as a guide and seat for loosely receiving the outer element 34 of the adjustable, expansible assembly. The opening surrounded between the flange 58 is coaxial with the barrel 2. Although this opening serves as a guide for the expansible assembly, it permits' free oating movement of said assembly axially through the same. l

Although the hub herein described is constructed to have both horizontal and vertical balance, it is difficult in practice to produce a hub having exact balance. In order to correct any inaccuracies in balance, the present invention provides on each end of the hub barrel a seat for a balancing weight. As shown in the drawings, each end of the barrel is provided with a ange 55 which serves as a stop against which a split ring or strap Sil surrounding the end portion of the barrel engages. Axed to each end of the strap 55 is a socket element 6|. These socket elements are provided with a centrally apertured closure at one end thereof with their open ends lying adjacent the end of the strap. Said socket elements are arranged to lie in axial alignment when the strap is positioned about the hub barrel to form a receptacle for a plurality of small washer-like lead weights 62. The lead weights ere ineieteirieil eieekee relaties agissent one elle .0f :the ,reeeeteele .Previeleslxbv the juxtaposed Seebei members.- .e eempressien spring 63 p0- sitioned between the end o; `the stock of lead Washers .eetl the eppeeite elesed eed 0i one of the testet merite .serves te maintain seid washers in position, Aloolt $4 lit/ted with a nut 6 5 passes esgiella ihrer-leb `tlie .seelsets end stack of weights and serves to draw the ends of the strap together .te-.bied the .Seme Ourthe hub barrel 'Tile elli-aber Q f Weiber-.like leed `Weights po- Sitieeed the .Seeleet member may be varied to brine tbe .heb iet@ lieriseifitei balance After the betleeetel beleuee `.iles been eiieeted.. ene 0r beth ai the steers may be rotated about, the barrel iii, tire eieeer direetien until vertical belette of the heb is tbteiiied- '.lhe straps .may then be teilieileii eli tbe barrel t0 prevent .further diS- Pleeemerlt .by drawing up tbe .eilt 65 en the belt 5f It will. be erntet-zielte@ from the iereeeirie deserirtiee tliet tbe present invention provides im- Rifeiied strutture ier the vtimidi-lling ef blade Cerf ifviree sleeves .wi-thin tlie. hub 0.1. a preeeller for free, unrestricted, synchronized movement there- Iii audities, the .strutture ef the present .iiiveiitieii provides ier the. etieetive. sealing of the assembly se that' there. will be ne less 0f lubrifiant iremtlee assembly .eine vet there will be very little fif 121.911 between the. blade Carrying sleeves and the beviel eftlie. hule .thereby permitting the blades carried by the sleeves to automatically assuine piteli. Changing positions .in response t0 eeniiitioiis oiflieht.

Apart. from the foregoing. tbe present invention provides a simple, novel construction which serres as. e step. for limiting rotary movement ef the blade Carrying sleeves and also serves. as e guide for an adjustable, expansible mechanism interposed between the ends of the blade carryine sleeves. te load bearings interposed between said Sleeves and the barrel o4 the hub.

We claim.;

1. Ahub construction for variable pitch propellers comprising Aa tubular blade mounting member open at both ends for the reception of blade carrying members rotatably mounted in each of said open ends, means associated with the open endsofsaid tubular mounting member for blockingoutward movement or said blade carry? ii ing members, a pair of telescoped'threadedly interconnected elements, one of said elements engaging the inner end portion of one of said blade carrying members and the other of said elements engaging the. inner end portion of the other of said blade carrying members, the inner of said elements having a splined bore andthe outer of said elements` having a slotted end portion, a locking member having a splined external sur-` face for insertionY in said splined bore and a head for engagement with the slotted portion to lock said elernents against relative. rotation.

2,-. A. ,heb construction for variable pitch propellers comprising a tubular blade mounting member open at both ends for the reception of blade carrying members rotatably mounted in each of said open ends, means associated with the open ends of said tubular mounting member for blocking outward movement .of said blade carrying members, a pair of telescoped threadedly interconnected elements, one of said elements engaging the inner end portion of one of said blade carrying members and the other of said elements engaging the inner end portion ofv the other of said blade carrying members, the in-V ner of said elements having a splined bore and the outer of said elements having a slotted eX- ternal end portion, a bolt-like locking member including a body portion having a splined intermediate portion for reception within said splined bore, a threaded portiony at one end and a head at the other end for engagement with said slotted portion, and means cooperating with Said threaded end of said bolt-like member to retain said head in locking engagement with said slotted portion.

3. In a variable pitch propeller, a hub having a pair of axially aligned blade-shank-receiving sockets formed thereon, a flanged blade-shankreceiving sleeve mounted for rotation in each socket, a blocking member in each socket, a thrust bearing surrounding each sleevel and interposed between the flange thereof and the blocking member in the socket in which the sleeve is mounted to limit outward movement of the sleeves in said sockets, a second thrust bearing carried by each sleeve at the inner end thereof, a pair of telescoped, threadedly interengaged tubular elements positioned between the inner ends or" said sleeves, each of said elements having a journal respectively inone of said last named thrust bearings, said elements being relatively extensible axially by relative rotation thereof to equally urge said sleeves outwardly of the sockets, and a rigid locking member having a non-rotary connection with both of said elements in the exten-ded position thereof to inhibit relative rotation thereof.

PAUL F. HACKETHAL. ROMUALD KAREY.

REFERENCES CITED The following references are of record in the lile of this patent:

UNITED STATES PATENTS Number Name Date 1,918,121 Mulhern July 11, 1933 2,094,149 Gaba V V r Sept.l 28, 1937 2,318,486 Hoover May 4, 1943. `2,370,657 Hackethal Mar. 5, 19.45

FOREIGN PATENTS Number Country Date 486,614 Great. Britain x June 8, 19.38 

